Software exists for allowing users to annotate various machine-based visual media objects, such as electronic text documents and electronic images. For example, it is known that readers can post comments about articles and other material they read on web pages. It is also known that authors and readers of electronic documents, such as Microsoft Word documents and portable document format (pdf) documents, can highlight selected text and/or images and provide comments on the selected items using electronic tools such as comment balloons and electronic “sticky notes.” In addition, software exists that allows multiple users to share highlighting, comments, and bookmarks with one another, for example, via various e-book-reader platforms, such as tablet computers and dedicated e-book reader devices.